Tribune Publishing hit a new 52-week low of $13.13 in intra-day trading Tuesday before closing at $13.17, down 5.8 percent — suggesting there may be some hurdles as the McClatchy Company tries to close the deal for the newspaper giant.

McClatchy, which is not officially out of it, our sources say, has its executives doing due diligence and visiting some of the papers involved in a potential sale.

“It’s still McClatchy’s to lose, but if it doesn’t happen this week, it may not happen at all,” said one source close to the situation. “It’s evolving by the hour.”

But there is growing concern from McClatchy that the Justice Department would frown on one company owning both the Miami Herald — currently one of the biggest newspapers McClatchy publishes — and the nearby Sun Sentinel, which Tribune owns.

The Tribune’s other papers, including the Chicago Tribune, the Baltimore Sun and the troubled New York Daily News, wouldn’t likely be considered problematic to the Justice Department. But taking Florida papers out of the mix means fewer chances for money-saving synergies.

Meanwhile, the Donerail Group, headed by former Starboard executive Will Wyatt, is also said to be ready to pounce if McClatchy officially drops out. If he emerges as the main suitor, he’d be using a “buy to bust it up” strategy, sources say.

While Wyatt is not negotiating with Tribune’s board at the moment, he is quietly contacting potential bidders for the various pieces should the deal come back to him. One source said he probably has parties interested in “about 75 percent of the company” in a bust-up.